<?php

namespace GetId3\Module\Archive;

use GetId3\Lib\Helper;
use GetId3\GetId3Core;

/////////////////////////////////////////////////////////////////
/// GetId3() by James Heinrich <info@getid3.org>               //
//  available at http://getid3.sourceforge.net                 //
//            or http://www.getid3.org                         //
/////////////////////////////////////////////////////////////////
// See readme.txt for more details                             //
/////////////////////////////////////////////////////////////////
//                                                             //
// module.archive.gzip.php                                     //
// module for analyzing GZIP files                             //
// dependencies: NONE                                          //
//                                                            ///
/////////////////////////////////////////////////////////////////
//                                                             //
// Module originally written by                                //
//      Mike Mozolin <teddybearØmail*ru>                       //
//                                                             //
/////////////////////////////////////////////////////////////////

/**
 * module for analyzing GZIP files
 *
 * @author James Heinrich <info@getid3.org>
 * @author Mike Mozolin <teddybearØmail*ru>
 *
 * @link http://getid3.sourceforge.net
 * @link http://www.getid3.org
 */
class Gzip
{
    /**
     * Optional file list - disable for speed.
     * decode gzipped files, if possible, and parse recursively (.tar.gz for example)
     *
     * @var bool
     */
    public $option_gzip_parse_contents = false;

    /**
     * @return bool
     */
    public function analyze()
    {
        $info = &$this->getid3->info;

        $info['fileformat'] = 'gzip';

        $start_length = 10;
        $unpack_header = 'a1id1/a1id2/a1cmethod/a1flags/a4mtime/a1xflags/a1os';
        //+---+---+---+---+---+---+---+---+---+---+
        //|ID1|ID2|CM |FLG|     MTIME     |XFL|OS |
        //+---+---+---+---+---+---+---+---+---+---+

        if ($info['filesize'] > $info['php_memory_limit']) {
            $info['error'][] = 'File is too large ('.number_format($info['filesize']).' bytes) to read into memory (limit: '.number_format($info['php_memory_limit'] / 1048576).'MB)';

            return false;
        }
        fseek($this->getid3->fp, 0);
        $buffer = fread($this->getid3->fp, $info['filesize']);

        $arr_members = explode("\x1F\x8B\x08", $buffer);
        while (true) {
            $is_wrong_members = false;
            $num_members = intval(count($arr_members));
            for ($i = 0; $i < $num_members; ++$i) {
                if (strlen($arr_members[$i]) == 0) {
                    continue;
                }
                $buf = "\x1F\x8B\x08".$arr_members[$i];

                $attr = unpack($unpack_header, substr($buf, 0, $start_length));
                if (!$this->get_os_type(ord($attr['os']))) {
                    // Merge member with previous if wrong OS type
                    $arr_members[$i - 1] .= $buf;
                    $arr_members[$i] = '';
                    $is_wrong_members = true;
                    continue;
                }
            }
            if (!$is_wrong_members) {
                break;
            }
        }

        $info['gzip']['files'] = array();

        $fpointer = 0;
        $idx = 0;
        for ($i = 0; $i < $num_members; ++$i) {
            if (strlen($arr_members[$i]) == 0) {
                continue;
            }
            $thisInfo = &$info['gzip']['member_header'][++$idx];

            $buff = "\x1F\x8B\x08".$arr_members[$i];

            $attr = unpack($unpack_header, substr($buff, 0, $start_length));
            $thisInfo['filemtime'] = Helper::LittleEndian2Int($attr['mtime']);
            $thisInfo['raw']['id1'] = ord($attr['cmethod']);
            $thisInfo['raw']['id2'] = ord($attr['cmethod']);
            $thisInfo['raw']['cmethod'] = ord($attr['cmethod']);
            $thisInfo['raw']['os'] = ord($attr['os']);
            $thisInfo['raw']['xflags'] = ord($attr['xflags']);
            $thisInfo['raw']['flags'] = ord($attr['flags']);

            $thisInfo['flags']['crc16'] = (bool) ($thisInfo['raw']['flags'] & 0x02);
            $thisInfo['flags']['extra'] = (bool) ($thisInfo['raw']['flags'] & 0x04);
            $thisInfo['flags']['filename'] = (bool) ($thisInfo['raw']['flags'] & 0x08);
            $thisInfo['flags']['comment'] = (bool) ($thisInfo['raw']['flags'] & 0x10);

            $thisInfo['compression'] = $this->get_xflag_type($thisInfo['raw']['xflags']);

            $thisInfo['os'] = $this->get_os_type($thisInfo['raw']['os']);
            if (!$thisInfo['os']) {
                $info['error'][] = 'Read error on gzip file';

                return false;
            }

            $fpointer = 10;
            $arr_xsubfield = array();
            // bit 2 - FLG.FEXTRA
            //+---+---+=================================+
            //| XLEN  |...XLEN bytes of "extra field"...|
            //+---+---+=================================+
            if ($thisInfo['flags']['extra']) {
                $w_xlen = substr($buff, $fpointer, 2);
                $xlen = Helper::LittleEndian2Int($w_xlen);
                $fpointer += 2;

                $thisInfo['raw']['xfield'] = substr($buff, $fpointer, $xlen);
                // Extra SubFields
                //+---+---+---+---+==================================+
                //|SI1|SI2|  LEN  |... LEN bytes of subfield data ...|
                //+---+---+---+---+==================================+
                $idx = 0;
                while (true) {
                    if ($idx >= $xlen) {
                        break;
                    }
                    $si1 = ord(substr($buff, $fpointer + $idx++, 1));
                    $si2 = ord(substr($buff, $fpointer + $idx++, 1));
                    if (($si1 == 0x41) && ($si2 == 0x70)) {
                        $w_xsublen = substr($buff, $fpointer + $idx, 2);
                        $xsublen = Helper::LittleEndian2Int($w_xsublen);
                        $idx += 2;
                        $arr_xsubfield[] = substr($buff, $fpointer + $idx,
                                                  $xsublen);
                        $idx += $xsublen;
                    } else {
                        break;
                    }
                }
                $fpointer += $xlen;
            }
            // bit 3 - FLG.FNAME
            //+=========================================+
            //|...original file name, zero-terminated...|
            //+=========================================+
            // GZIP files may have only one file, with no filename, so assume original filename is current filename without .gz
            $thisInfo['filename'] = preg_replace('#\.gz$#i', '',
                                                 $info['filename']);
            if ($thisInfo['flags']['filename']) {
                while (true) {
                    if (ord($buff[$fpointer]) == 0) {
                        ++$fpointer;
                        break;
                    }
                    $thisInfo['filename'] .= $buff[$fpointer];
                    ++$fpointer;
                }
            }
            // bit 4 - FLG.FCOMMENT
            //+===================================+
            //|...file comment, zero-terminated...|
            //+===================================+
            if ($thisInfo['flags']['comment']) {
                while (true) {
                    if (ord($buff[$fpointer]) == 0) {
                        ++$fpointer;
                        break;
                    }
                    $thisInfo['comment'] .= $buff[$fpointer];
                    ++$fpointer;
                }
            }
            // bit 1 - FLG.FHCRC
            //+---+---+
            //| CRC16 |
            //+---+---+
            if ($thisInfo['flags']['crc16']) {
                $w_crc = substr($buff, $fpointer, 2);
                $thisInfo['crc16'] = Helper::LittleEndian2Int($w_crc);
                $fpointer += 2;
            }
            // bit 0 - FLG.FTEXT
            //if ($thisInfo['raw']['flags'] & 0x01) {
            //	Ignored...
            //}
            // bits 5, 6, 7 - reserved

            $thisInfo['crc32'] = Helper::LittleEndian2Int(substr($buff,
                                                                            strlen($buff) - 8,
                                                                                   4));
            $thisInfo['filesize'] = Helper::LittleEndian2Int(substr($buff,
                                                                               strlen($buff) - 4));

            $info['gzip']['files'] = Helper::array_merge_clobber($info['gzip']['files'],
                                                                            Helper::CreateDeepArray($thisInfo['filename'],
                                                                                                               '/',
                                                                                                               $thisInfo['filesize']));

            if ($this->option_gzip_parse_contents) {
                // Try to inflate GZip
                $csize = 0;
                $inflated = '';
                $chkcrc32 = '';
                if (function_exists('gzinflate')) {
                    $cdata = substr($buff, $fpointer);
                    $cdata = substr($cdata, 0, strlen($cdata) - 8);
                    $csize = strlen($cdata);
                    $inflated = gzinflate($cdata);

                    // Calculate CRC32 for inflated content
                    $thisInfo['crc32_valid'] = (bool) (sprintf('%u',
                                                               crc32($inflated)) == $thisInfo['crc32']);

                    // determine format
                    $formattest = substr($inflated, 0, 32774);
                    $getid3_temp = new GetId3Core();
                    $determined_format = $getid3_temp->GetFileFormat($formattest);
                    unset($getid3_temp);

                    // file format is determined
                    $determined_format['module'] = (isset($determined_format['module']) ? $determined_format['module'] : '');
                    switch ($determined_format['module']) {
                        case 'tar':
                            // view TAR-file info
                            if (class_exists($determined_format['class'])) {
                                if (($temp_tar_filename = tempnam(GetId3Core::getTempDir(),
                                                                  'getID3')) === false) {
                                    // can't find anywhere to create a temp file, abort
                                    $info['error'][] = 'Unable to create temp file to parse TAR inside GZIP file';
                                    break;
                                }
                                if ($fp_temp_tar = fopen($temp_tar_filename,
                                                         'w+b')) {
                                    fwrite($fp_temp_tar, $inflated);
                                    fclose($fp_temp_tar);
                                    $getid3_temp = new GetId3Core();
                                    $getid3_temp->openfile($temp_tar_filename);
                                    $getid3_tar = new Tar($getid3_temp);
                                    $getid3_tar->analyze();
                                    $info['gzip']['member_header'][$idx]['tar'] = $getid3_temp->info['tar'];
                                    unset($getid3_temp, $getid3_tar);
                                    unlink($temp_tar_filename);
                                } else {
                                    $info['error'][] = 'Unable to fopen() temp file to parse TAR inside GZIP file';
                                    break;
                                }
                            }
                            break;

                        case '':
                        default:
                            // unknown or unhandled format
                            break;
                    }
                }
            }
        }

        return true;
    }

    /**
     * Converts the OS type
     *
     * @staticvar array $os_type
     *
     * @param  type $key
     *
     * @return type
     */
    public function get_os_type($key)
    {
        static $os_type = array(
            '0' => 'FAT filesystem (MS-DOS, OS/2, NT/Win32)',
            '1' => 'Amiga',
            '2' => 'VMS (or OpenVMS)',
            '3' => 'Unix',
            '4' => 'VM/CMS',
            '5' => 'Atari TOS',
            '6' => 'HPFS filesystem (OS/2, NT)',
            '7' => 'Macintosh',
            '8' => 'Z-System',
            '9' => 'CP/M',
            '10' => 'TOPS-20',
            '11' => 'NTFS filesystem (NT)',
            '12' => 'QDOS',
            '13' => 'Acorn RISCOS',
            '255' => 'unknown',
        );

        return (isset($os_type[$key]) ? $os_type[$key] : '');
    }

    /**
     * Converts the eXtra FLags
     *
     * @staticvar array $xflag_type
     *
     * @param  type $key
     *
     * @return type
     */
    public function get_xflag_type($key)
    {
        static $xflag_type = array(
            '0' => 'unknown',
            '2' => 'maximum compression',
            '4' => 'fastest algorithm',
        );

        return (isset($xflag_type[$key]) ? $xflag_type[$key] : '');
    }
}
